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OPERATION
ZEISS
Illumination and contrast methods in reflected light …
Axioscope 5/7/Vario
120
430035-7344-001
03/2018
4.3.5
Setting reflected light polarization – proof of bireflectance and reflection
Pleochroism
(1) Application
Reflected light polarization is a contrasting method suited for cut surfaces of mineral ore, coal, ceramics,
special metals and alloys. Depending on the orientation of the crystals and the specimen details, the cut
surfaces often react differently when reflected in linearly polarized light.
The illumination light is polarized by the polarizer before passing through the objective onto the
specimen surface where it is reflected. Then the beam parts experience path differences depending on
the structure and polarization of optical rotations which, when passing through the analyzer, are
represented by different shades of gray. With the aid of a compensator with a
λ
-plate the gray contrast
can be converted into a color contrast.
Caution! Do not use a 6x20 mm compensator for this
conversion!
Even when examining "dark" specimen surfaces, a rotatable
λ
/4 plate in front of the objective (anti-
reflective cap) helps eliminate the reflections which are inevitable when working with objectives with very
low scale figures.
(2) Instrumentation
−
Axioscope with pre-installed LED 10 W illuminator or optionally used with HAL 100 halogen lamp
mounted at the back of the upper part of the stand
−
Pol rotary stage
−
Objectives: Epiplan-Neofluar Pol, EC Epiplan-Neofluar Pol, Epiplan Pol
−
DIC P&C or DIC Rot I P&C reflector module in the reflector turret/slider
or Pol P&C reflector module plus analyzer slider
or analyzer slider plus polarizer slider
(3) Setting reflected light polarization
•
Adjust the microscope for reflected light brightfield microscopy as described in section 4.3.1.
•
If using the objective position with a DIC position, remove the DIC slider, if necessary.
•
Swing the DIC P&C reflector module (
4
) on the reflector turret into the beam path, swing in
the Pol P&C reflector module and slide the analyzer slider into the compartment; or slide the analyzer
slider (
1
) and the polarizer slider (
2
) into their compartments, if applicable. When
using the fixed sliders, the polarizer must be aligned in the EAST-WEST direction and the analyzer in
the NORTH-SOUTH direction.
•
Place the sample on the stage, adjust the desired magnification, focus, and examine the sample in the
polarization contrast which is now present while turning the Pol rotary stage (
3
).